I am a lifelong vegetarian. My mother always was (got it from her parents) and my father became vegetarian when he met my mother. So me and my sisters grew up without meat/fish.
I’m completely healthy, as are they. And I don’t take any food supplements at all.
Reasons? As Sam2 says, I find the treatment of animals in the meat industry apprehensive. But even without that – I simply grew up like this and will never change it. The thought of putting something in my mouth that was once walking around and had a brain, eyes, ears and bones, makes me totally sick. I will never in my life eat meat, and I don’t care what anyone thinks about that.
By the way, it’s interesting to know that on the same piece of ground on which you could put animals to get meat to feed 50 people, you could grow vegetables to feed 200 people (not sure of the exact ciphers, but I know the principle is true). It is a fact that if the entire world would cease eating meat, there would be no hunger and starvation in the world, and every person in the world would have plenty of food, even if the world had not 8 but 20 billion inhabitants.